This invention relates generally to conveying devices of the type used to move workpieces from a feeding to a receiving apparatus in a desired orientation.
In mechanical processing operations such as machining, inspection or the assemblying of parts, tracks are frequently used to transport a given part, or workpiece, from one apparatus to another. For example, a vibratory feeder may be used to organize a collection of workpieces into a continuous stream for inspection by a machine which classifies the workpieces according to their size. In order to transport the workpieces from the vibratory feeder's outlet to the classifying machine in the desired orientation for measurement, the two machines are connected by a track which is designed according to the particular shape and size range of the workpieces.
Currently available track designs are substantially rigid structures, typically utilizing truss or sheet metal construction for the supporting framework. Handmade or custom molded channels attached to the framework are used for guiding the workpieces in a desired orientation between the feeding and receiving apparatus. Such tracks are complex structures which cannot be mass produced, having many parts which must be individually designed or constructed for a single purpose application. Assembly of the structure typically requires extensive welding or soldering, which is both costly and time consuming. Furthermore, the structure cannot thereafter be easily disassembled for routine maintenance and replacement of parts. The resulting structure is therefore expensive to build and service.
Some of the disadvantages of channel-type tracks have been alleviated by the use of so-called wire guide tracks, in which the track structure comprises a number of rigid wires arranged parallel to each other in a fixed lateral relationship according to the size and shape of a workpiece to be conveyed by the track. The wires are welded to a number of alignment frames which hold the wires in fixed position relative to each other, and the resulting track is held rigid by a supporting framework. While such structures may be simpler to design than channel-type tracks, their rigid, welded construction and supporting framework still result in high construction and maintenance costs. Further, the design of such wire tracks to date has not permitted workpieces carried by the track to be rotated from one angular orientation to another (viewed in a plane normal to the workpiece's direction of travel) as the workpiece moves along the track. Such rotation must be performed by channel-type tracks external to the wire track, thus limiting the wire track's usefulness.
In addition to the high cost of prior art tracks, several other disadvantages arise from their rigid structures. Once a track is designed to interconnect a particular feeding apparatus with a receiving apparatus, the geometry of the track is set and the two connected apparatus cannot thereafter be shifted relative to each other without redesigning the track. Further, when a rigid track is intended for use with a vibratory feeder, the track may not be directly attached to the feeder without damping the feeder's vibration, thus requiring mechanical isolation of the feeder from the track. This not only complicates the transfer of workpieces from the vibratory feeder to the track, but also prevents the utilization of the feeder's vibration for freeing jammed workpieces in the track. Instead, separate accelerators may be required to help move workpieces through the track, thus adding to the cost, complexity and maintenance requirements of the structure.